An OLD Ammo question..

[Mr. 16 gauge]

Could it be ammo for an early breech loader, such as an 1863 Sharps (or similar rifle)? The 1863 used a nitrated paper cartridge. The lever was dropped to expose the breech; the cartridge was inserted and when the breech closed, it 'sheared' off the back of the cartridge, exposing the powder. A percussion cap was then placed on the nipple, similar to a regular percussion muzzleloader, and the the gun was cocked and fired. The nitrated paper burned quickly, and then the process was repeated.

Just a guess....here is more on the sharps.

http://www.shilohrifle.com/